OBJECTIVE: To explore the genetic pathogenesis of X-linked agammaglobulinemia in two patients for clinical diagnosis and family counseling. METHODS: Data was collected from the patients' family including clinical information, blood immunoglobulin level, as well as classification and subgrouping of B lymphocytes. Gene mutations were screened by whole exome sequencing (WES) through next-generation sequencing (NGS), the result was verified with Sanger sequencing. RESULTS: A BTK c.1627T>C (p.Ser543Pro) variant was found in the pedigree. The phenotype and variant have co-segregated in the pedigree. The variant was not found in population database. The variant has affected in the kinase domain which contained no benign variants and is harmful as predicted through bioinformatic analysis. CONCLUSION BTK c.1627T>C (p.Ser543Pro) is a pathogenic variant contributing to X-linked agammaglobulinemia in this pedigree. Above finding has provided reproduction guidance for this family.
Agammaglobulinaemia Tyrosine Kinase/genetics* ; Agammaglobulinemia/genetics* ; DNA Mutational Analysis ; Genetic Diseases, X-Linked ; Humans ; Mutation ; Pedigree

Fabry's disease is an X-linked lysosomal storage disorder caused by abnormalities in the alpha-galactosidase A (GLA) gene, which leads to a GLA deficiency and to the intracellular deposition of globotriaosylceramide (Gb3) within vascular endothelium and other tissues. It manifests as progressive multiple organ dysfunctions caused by the deposition of Gb3. On the other hand, congenital agammaglobulinemia is usually caused by mutations in Bruton's tyrosine kinase (Btk) gene with X-linked dominence, suppresses B cell maturation, and causes recurrent pyogenic infections. In former reports, the distance between the loci in the Xq22 region of the human X chromosome was found to be about 69 kilobases. A 23-yr-old man diagnosed with congenital agammaglobulinemia at age 5, showed typical clinical and laboratory and histopathological findings of Fabry's disease. The genetic basis of this combination of the two syndromes was studied in this patient. Here, we report a case of Fabry's disease with congenital agammaglobulinemia.
Adult ; Agammaglobulinemia/congenital/*genetics/pathology ; Chromosomes, Human, X ; Fabry Disease/diagnosis/*genetics ; Humans ; Kidney/pathology ; Male ; Microscopy, Electron ; Sequence Analysis, DNA ; Skin/pathology ; alpha-Galactosidase/genetics/metabolism

OBJECTIVEMutation in the heavy chain micro (microHC) gene causes a rare type of autosomal recessive agammaglobulinemia. Here we report the molecular and clinical characterization of a compound heterozygous mutation in the microHC gene in a patient with autosomal recessive agammaglobulinemia firstly from China.

METHODA one-year and ten-month-old male patient and his parents were enrolled in this study. No mutation was found in BTK gene. The microHC gene of the patient and his parents were amplified by polymerase chain reaction (PCR) from genomic DNA. Reverse transcription polymerase chain reaction (RT-PCR) was used to amplify the microHC transcripts. Sequencing was performed directly on the PCR products bidirectionally.

RESULTSSince 8 months of age, the patient had had recurrent fever and persistent cough. He suffered an acute right hemiplegia at 11 months of age and swelling and pain of left hip joint and right knee joint at one year and eight months of age. Cerebrospinal fluid routine examination showed that total cell count was 18 x 10(6)/L [normal range (0 - 15) x 10(6)/L], leukocyte count 7 x 10(6)/L [(0 - 15) x 10(6)/L] and biochemical examination showed protein 0.14 g/L (0.15 - 0.45 g/L), glucose 4.68 mmol/L (2.44 - 4.44 mmol/L) and chloride 116.3 mmol/L (120 - 132 mmol/L). Mycobacterium bovis was identified negative by cerebrospinal fluid smear examination. No obvious abnormity was detected on skull CT examination. Hydrothorax examination showed that total cell count was 848 x 10(6)/L, leukocyte count 785 x 10(6)/L and protein 30.8 g/L (< 30 g/L). Poliovirus isolation from stool sample of the patient was negative. The serum immunoglobulin (Ig) profile was IgG 181 mg/L (normal range, 5.09 - 10.09 g/L); IgM 28.8 mg/dl (400 - 1260 mg/dl) and IgA 22 mg/dl (310 - 670 mg/dl), IgE 4.6 U/ml (normal range < 150 U/ml). There were no B-cells but normal percentage of T-cells (67%) and NK cells (32%) were present in the peripheral blood. The patient had a compound heterozygous mutation in the microHC gene:on one allele, there was an alternative splice site mutation in exon 4 (1956 G > A), for which the patient's father was a carrier. Whereas on the other allele, an insert mutation between 170 and 175 in exon 1 with a premature stop codon (170 - 175 insert C, L11fs60X) was identified, for which the patient's mother was a carrier. The insert mutation in exon 1 of microHC gene was firstly reported. To detect the effect of the splice site mutation in exon 4, microHC cDNA of the patient was amplified by semi-nested PCR. The PCR products were purified and sequenced directly. A 136 bp of intron 4 was found in the transcripts and only the secreted isoform with a missense substitution is present in the patient, while synthesis of the membrane isoform is completely abolished.

CONCLUSIONThis is the first case with autosomal recessive agammaglobulinemia with compound heterozygous mutation in the microHC gene reported from China. A novel mutation in exon 1 was found.

Agammaglobulinemia ; congenital ; genetics ; Asian Continental Ancestry Group ; genetics ; Base Sequence ; DNA ; genetics ; DNA, Complementary ; genetics ; Exons ; Heterozygote ; Humans ; Immunoglobulin mu-Chains ; genetics ; Infant ; Male ; Molecular Sequence Data ; Mutation ; Polymerase Chain Reaction

PURPOSE: X-linked agammaglobulinemia (XLA) is a humoral immunodeficiency disease caused by a mutation in the Bruton tyrosine kinase (BTK) gene resulting in defective B cell differentiation. Because it is a relatively rare disorder, it is difficult for clinicians to have a comprehensive understanding of XLA due to a lack of exposure to the disease. Clinical presentations of patients with XLA were analyzed and discussed to improve care plans. MATERIALS AND METHODS: During a 20 year period, from January 1987 to June 2006, a total of 19 patients were diagnosed as XLA in the Department of Pediatrics at Severance Hospital, Seoul, Korea. A retrospective analysis of the clinical presentations of those patients was performed. RESULTS: The mean age of the XLA patients included in the study was 4.89 years, with a range of 6 months to 13 years. Twelve patients were diagnosed before age 5, while the other 7 patients were diagnosed after age 5. Recurrent infections observed in the patients included pneumonia, acute otitis media, septic arthritis, skin infection, sepsis, sinusitis, acute gastroenteritis, cervical lymphadenitis, epididymitis, meningitis, osteomyelitis, urinary tract infection and encephalitis. Frequency of admissions was variable from 0 to 12 times, depending on the time at which immunoglobulin therapy was started. Six cases had family histories positive for XLA. BTK gene mutations were found in 8 cases. CONCLUSION: The overall prognosis of XLA is good as long as patients are diagnosed and treated early with regular intra venous gamma globulin therapy before the sequelae of recurrent infections appear.
Adolescent ; Agammaglobulinemia/complications/*diagnosis/drug therapy/genetics ; Child ; Child, Preschool ; Genetic Diseases, X-Linked/enzymology/genetics/pathology ; *Hospitals ; Humans ; Infant ; Male ; Protein-Tyrosine Kinases/genetics/metabolism ; Retrospective Studies ; Time Factors

OBJECTIVETo explored the relationship between genotype of Bruton's tyrosine kinase (BTK) gene and X-linked agammaglobulinemia (XLA).

METHODSSix patients who were clinically suspected as XLA based on immunological results were studied. Peripheral blood samples were collected for DNA extraction. The 19 exons and exon-intron boundaries of the BTK gene were amplified by PCR, and the products were directly sequenced.

RESULTSAll of the 6 patients were confirmed to have XLA due to the mutations in exons of the BTK gene. Among these, 3 mutations were located in the kinase domain (TK), 2 were located in pleckstrin homology (PH) domain, and 1 was located in Src homology (SH2) domain. The mutations have included 3 missense mutations, i.e., c.1105C to T (p.L369F), c.82C to T(p.R28C) and c.1754T to C (p.V585A), 2 nonsense mutations, i.e., c.1834C to T (p.Q612X) and c.37C to T (p.R13X). One patient was found to have complex (missense and nonsense) mutations, i.e., c.1802-1803TT to GC (p.F601C) and c.1803-1804insC (p.T602fsX603). There were 3 novel mutations (p.F601C, p.T602fsX603 and p.V585A). The mothers of 5 patients were also detected with BTK gene mutations, among whom 4 were demonstrated to be carriers and one was normal (her son had p.V585A mutation). Therefore, p.V585A was a de novo mutation.

CONCLUSIONDetection of BTK gene mutation can confirm clinical diagnosis which is critical for patients to take regular immunoglobulin replacement therapy for life. Early genetic diagnosis can also identify carriers and make genetic counseling possible.

Agammaglobulinemia ; enzymology ; genetics ; Base Sequence ; Child ; Child, Preschool ; Codon, Nonsense ; Female ; Genetic Diseases, X-Linked ; enzymology ; genetics ; Genotype ; Humans ; Male ; Molecular Sequence Data ; Mutation, Missense ; Protein-Tyrosine Kinases ; genetics

OBJECTIVEX-linked agammaglobulinemia (XLA) is the most common disorder among primary immunodeficiency diseases, which is caused by mutations in the cytoplasmic Bruton's tyrosine kinase (BTK) gene, characterized by lack of mature, circulating B lymphocytes, hypogammaglobulinemia, and recurrent bacterial infections. Mutations in BTK are highly diverse. In this study, genetic analysis was performed on BTK to realize the feature of gene mutation of XLA in Mainland of China.

METHODSSeven patients from 7 different families were enrolled in the analysis. RT-PCR was employed to reverse transcript total RNA and 8 couples of primers were designed for PCR. PCR products were sequenced and the mutation sites were identified.

RESULTSSeven completely different mutations were identified in the 7 patients. All the 7 mutations located at BTK coding region. Three of the 7 mutations were located in pleckstrin homology functional area, 2 mutations located in BTK area, and in other 2 cases at Src homology 2 and Src homology 3 regions, respectively. The mutations in 2 of 7 cases were in exon 18, and the others were in exon 2, 5, 6, 8 and 10, respectively. The types of mutation included 3 missense (L11P, I590F and Y591S), two nonsense (W281X, and Q234X) mutations resulting in premature stop codons. A 10-base pair nucleotides duplicated insertion located between the nucleotide 596 and 597 resulting in frameshift, and a 8 base pair deletion at the nucleotide position 472 resulting in frameshift. Four of the 7 mutations are novel mutation types and have not been reported. Four of 7 mothers were analyzed, 3 of them were carrier and 1 was normal.

CONCLUSIONThe patients enrolled in this study had classical clinical features of XLA. All the 7 identified mutations located at BTK coding region and 4 of them were novel mutations. Genetic analysis can be used for diagnosis of XLA and distinguish it from other hypogammaglobulinemia.

Adolescent ; Agammaglobulinemia ; diagnosis ; genetics ; Base Sequence ; Child ; China ; Codon, Nonsense ; DNA, Complementary ; Genetic Diseases, X-Linked ; diagnosis ; genetics ; Genotype ; Humans ; Male ; Mutation ; Mutation, Missense ; Protein-Tyrosine Kinases ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; Young Adult

OBJECTIVEX-linked agammaglobulinemia (XLA), caused by mutations in Bruton's tyrosine kinase (BTK), is a common form of inherited antibody deficiency. There were very few case reports of this disease that were diagnosed only based on clinical findings in China. The purpose of this study was to evaluate the clinical features of 8 Chinese cases with XLA with BTK defect which were confirmed by flow cytometry and/or gene analysis.

METHODBased on clinical findings, 8 suspected XLA patients were confirmed by detecting the expression of BTK by flow cytometry and/or gene analysis of BTK. The history and thorough physical examination and routine immunological evaluation of 8 cases were collected and reviewed.

RESULTSThe age of onset of all the 8 male patients were from 3 months to 3 years. The mean age at diagnosis was 6 years. Recurrent upper respiratory infection and pneumonia with fever were seen in all the patients. Nasopharynx infection was mainly contributed to upper respiratory infection. Very few or no otitis (1/8) and sinusitis (0/8) were involved. Polyarthritis without evidence of infection was common (3/8). Chronic diarrhea was documented during the first 2 years after the onset of the disease in 2 cases. Two of the patients suffered from meningitis one time each. Skin infection was not serious in two patients. Osteomyelitis occurred in one case, which occurred secondary to a trauma. One case had poliomyelitis-like disease that was considered to be related to polio vaccine. Only two cases had unconfirmed maternal family history of XLA. The prominent signs at diagnosis were dystrophia, growth and developmental retardation and markedly decreased or absent tonsils and lymph nodes. Concentration of all classes of serum immunoglobulins (Igs) and the number of B cells in the peripheral circulation were dramatically decreased. The ratio of CD4/CD8 in most of the patients (6/8) was markedly inverse.

CONCLUSIONThe age at diagnosis of this reported group was older. Clinical symptoms displayed recurrent upper respiratory infection (nasopharynx infection but rare or no otitis or sinusitis) and pneumonia; polyarthritis was common. There were no confirmed family history of XLA. Most of the patients showed inverse ratios of CD4/CD8, the reason and potential significance are unclear.

Agammaglobulinemia ; complications ; diagnosis ; genetics ; Arthritis ; etiology ; CD4-CD8 Ratio ; Child ; Child, Preschool ; Flow Cytometry ; Humans ; Infant ; Male ; Mutation ; Nasopharyngeal Diseases ; etiology ; Pneumonia ; etiology ; Protein-Tyrosine Kinases ; genetics ; Recurrence ; Respiratory Tract Infections ; etiology

This research investigated the clinical features of immunodeficiency disease and the features of the mutation of its pathogenic genes. All 7 patients were boys aged 5 months to 4 years and 6 months and had a history of recurrent respiratory infection and pneumonia, low levels of IgM and IgG, and abnormal absolute values or percentages of lymphocyte subsets. High-throughput sequencing showed c.1684C>T mutations in the BTK gene in patient 1 and IVS8+2T>C splice site mutations in the BTK gene in patient 2. Both of these mutations came from their mothers. Patients 3, 4, and 5 had mutations in the IL2RG gene, i.e., c.298C>T, IVS3-2A>G, and c.164T>A, among which c.164T>A mutations had not been reported. Patient 6 had c.204C>G mutations in the RAG2 gene. Patient 7 had complex heterozygous mutations of c.913C>T and c.824G>A in the RAG2 gene, which came from his father and mother, respectively. Patients with immunodeficiency disease have abnormal immunological indices, and high-throughput sequencing helps to make a definite diagnosis.
Agammaglobulinaemia Tyrosine Kinase ; Agammaglobulinemia ; genetics ; Child, Preschool ; Computational Biology ; DNA-Binding Proteins ; genetics ; Genetic Diseases, X-Linked ; genetics ; High-Throughput Nucleotide Sequencing ; Humans ; Immunologic Deficiency Syndromes ; genetics ; therapy ; Infant ; Interleukin Receptor Common gamma Subunit ; genetics ; Male ; Mutation ; Nuclear Proteins ; genetics ; Protein-Tyrosine Kinases ; genetics